Adding users to notifications

The documentation says "This list can be modified by those who have proper permissions."...but what are those "proper permissions"?? Is it the 'super user' flag? Can the notification list only be updated by an admin user and/or the
creator?

The documentation says "This list can be modified by those who have proper permissions."...but what are those "proper permissions"?? Is it the 'super user' flag? Can the notification list only be updated by an admin user and/or
the creator?